The invention concerns more particularly but not exclusively spinal osteosynthesis devices of the type comprising a rod housed and locked in a certain number of fasteners constituted by an osseous anchorage section formed by a screw or bent-shaped plate and a rod fixing body constituted by a diapason-shaped head housing between its two branches said rod which is locked by means of an attachment screw housed in an internal screw thread fitted on the internal faces opposite said branches.
Usually, for example in the case where one vertebra of the spine is fractured, two osteosynthesis rods are fixed in parallel on both sides of the spine with the aid of fasteners secured to certain vertebrae.
This device is completed by transversal rendered-integral and traction devices interconnecting the two rods, generally constituted by transversal rods interconnecting hooks engaged on the two rods.
These devices are not practical to install and are of a type which may twist the rods owing to the traction they could exert on the latter.